Toe pieces of safety ski bindings

ABSTRACT

In a toe piece of a safety ski binding wherein the toe of the soleplate of the skier&#39;&#39;s boot is releasably clamped by a clamping member, there are provided a base plate having two spaced apart pins near the fore end and the rear end thereof respectively, a body pivotally mounted on the first pin located near the fore end and formed with a cam receiving chamber near the rear end thereof, a cam slidably received in the cam receiving chamber, a cam surface in the form of an arcuate recess formed at the center of the rear end surface of the cam, a compression spring contained in the body in the axial direction thereof for normally urging the cam surface against the second pin located near the rear end of the base plate, means for adjusting the spring, and a toe clamping member secured to the body at the end thereof whereby when a transverse force exceeding a predetermined safety limit preset by the spring is applied to the boot, the second pin is caused to be disengaged from the cam surface to allow the cam and the body to rotate about the first pin located near the fore end of the base plate thereby releasing the toe from the toe clamping member.

United States Patent [191 Murata et al.

[ Sept. 23, 1975 TOE PIECES OF SAFETY SKI BINDINGS [75] Inventors:Masahiro Murata; Michio Iizuka,

both of Tokyo. Japan [73] Assignce: Hope Kabushiki Kaisha, Tokyo,

Japan [22] Filed: Feb. 20, I974 [21] Appl. No.: 443.988

Primary E.\'uminerRobert R. Song Almrney, Agent. or FirmDiller. Brown,Ramik & Wight 1 ABSTRACT In a toe piece of a safety ski binding whereinthe toe of the soleplate of the skiers boot is releasably clamped by aclamping member. there are provided a base plate having two spaced'apartpins near the fore end and the rear end thereof respectively, a bodypivotally mounted on the first pin located near the fore end and formedwith a cam receiving chamber near the rear end thereof, a cam slidablyreceived in the cam receiving chamber. a cam surface in the form of anarcuate recess formed at the center of the rear end surface of the cam.a compression spring contained in the body in the axial directionthereof for normally urging the cam surface against the second pinlocated near the rear'end of the base plate. means for adjusting thespring, and a toe clamping member secured to the body at the end thereofwhereby when a transverse force exceeding a predetermined safety limitpreset by the spring is applied to the boot, the second pin is caused tobe disengaged from the cam surface to allow the cam and the body torotate about the first pin located near the fore end of the base platethereby releasing the toe from the toe clamping member.

8 Claims, 12 Drawing Figures US Patent Sept. 23,1975 shfiet 2 of 53,907,317

US Patant Sept. 23,1975 Sheet 3 of5 US Patent Sept. 23,1975 Sheet 4 of53,907,317

US Patent Sept. 23,1975 Sheet 5 of5 3,907,317

PIC-3.9

TOE PIECES OF SAFETY SKI BINDINGS BACKGROUND OF THE INVENTION Thisinvention relates to a safety ski binding and, more particularly, to atoe piece for releasably holding the toe of the soleplate of a ski boot.I

The safety ski binding usually comprises a toe piece for holding the toeof the soleplate and quickly releases the toe whenever a transverse loadapplied to the boot exceeds a predetermined safety limit or apermissible maximum load which may cause a serious injury to the skiersuch as a bone fracture, and a heel piece adapted to engage the rear endof the soleplate for applying thereto a forward pressure.

A prior art toe piece comprises a base plate secured to the ski, a bodypivotally mounted on the base plate so as to rotate about a pivot pinwhen the transverse force applied to the boot exceeds the safety limitand a toe clamping piece pivotally mounted on another pivot pin so as toreleasably engage the toe of the soleplate by the cooperation ofaresilient latching force applied by the body and the forward pressureapplied by the heel piece, thereby resiliently absorbing the shocksapplied to the boot during normal operation of the ski.

Since the ski binding is used under low temperature environments. itoften becomes inoperable due to deposition of snow or ice. Theconstruction described above is not desirable because it includes twopivot pins. Moreover. the toe piece of such construction requires alarge number of component parts and hence is complicated in constructionand expensive.

SUMMARY OF 'I HE INVENTION Accordingly, it is an object of thisinvention to provide a novel toe piece of an improved construction thatrequires only a single pivot pin.

A further object of this invention is to provide an improved toe piecerequiring a relatively small number of component parts and can bereadily fabricated into a rugged and simple construction.

Still further object of this invention is to provide an improved toepiece utilizing a cam made of a synthetic resinous material having selflubricating property thereby assuring a positive operation of the toepiece under an extremely low temperature environment.

According to this invention, these and further objects can beaccomplished by providing a toe piece of a safety ski binding of thetype including a rotatable toe clamping member which acts to normallyclamp the toe of the soleplate of a ski boot but is rotated to releasethe toe when a transverse force exceeding a predetermined limit isapplied to the boot, characterized in that the toe piece comprises abase plate to be secured to the ski, first and second pins which aresecured to the base plate near the fore end and the rear end thereofrespectively, a body pivotally mounted on the first pin located near thefore end. the body being provided with a cam receiving chamber near therear end thereof. a cam received in the cam receiving chamber to beslidable in the longitudinal direction of the axis of the ski, the rearend surface of the cam being provided with a recessed cam surfaceengageable with said second pin near the rear end of said base plate, acompression spring contained in the body in the axial direction thereoffor normally urging the recessed cam surface against the second pin.means for adjusting the force of the spring. and a toe clamping membersecured to the body at the rear end thereof, whereby when a transverseforce exceeding a predetermined safety limit preset by the spring isapplicd to the boot. the second pin is caused to be disengaged from thecam surface to allow the cam and the body to rotate about the first pinthereby releasing the toe from the toe clamping memher.

The toe clamping member has a cup shaped configuration and comprises asingle or two members connected to the body by means of a bolt or boltswhich is used to adjust the vertical position of the toe clampingmember.

The cam is preferably made of a self lubricating substance such astetrafluoroethylene.

BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings:

FIG. I is a top plan view, with the cover plate removed, of oneembodiment of the toe piece embodying the invention;

FIG. 2 shows a longitudinal sectional view of the toe piece shown inFIG. 1 taken along a line II II;

FIG. 3 is a bottom plan view of the body used in the toe piece shown inFIGS. 1 and 2;

FIG. 4 is a top plan view of the body;

FIG. 5 is a rear end view of the body;

FIG. 6 is a perspective view of the essential component elements of thetoe pieces shown in FIGS. 1 and 2;

FIG. 7 is a top plan view, partly broken away, of a modified toe pieceembodying the invention;

FIG. 8 is a longtitudinal sectional view of the toe piece shown in FIG.7 taken along a line VIII VIII;

FIG. 9 is a longitudinal sectional view of a modified toe pieceembodying the invention;

FIG. 10 is aperspective view, with the cover removed, of an assembly ofthe body and cam shown in FIG. 9;

FIG. 11 is a perspective bottom view of the cover utilized in the toepiece shown in FIG. 9 and FIG. 12 is a top plan view of the cover.

With referenceitovthe first embodiment of this inven- I tion shown inFIGS. 1 through 6, the toe piece of this invention comprises anelongated trapezoidal base plate 2 secured -to a ski l with itslongitudinal axis aligned with that of the ski. The base plate 2 isprovided with an upstanding pin 3 near its fore end and an upstandingpin 4 near its rear end, the pins 3 and 4 being positioned on the centerline of the base plate 2 and secured thereto by suitable fastening meanssuch as caulkings 3a and 4a. As shown in FIG. 1.. the base plate 2 isprovided with openings 2a on the rear side thereof for receiving machinescrews. not shown, utilized to securely fasten the base plate to theski.

A body 5 which has a generally elongated trapezoidal shape in its topplan view is mounted on the base plate 2. The contour of the fore halfof the body 5 generally conforms to that of the base plate 2, and a pairof arcuate recesses 51! are formed on both sides of the body to clearopenings 20. As best shown in FIGS. 3 and 4. the fore half of the body 5is provided with a cam receiving chamber 6 which is defined by two sidewalls 6a which are parallel to the axis of the body 5, and an arcuateend wall 612 concentric with the pin 3. The fore half of the body 5 isalso formed with a circular opening 7 for receiving the pin 3. The topplate of the body 5 which closes the top opening of the cam receivingchamber 6 is provided with an arcuate slot 8 concentric with the endwall 6!), the slot 8 receiving the reduced diameter portion 4/) near theupper end of the pin 4. A spring receiving opening 9 is provided toextend through the body 5 in the axial direction thereof from the foreend of the body to the fore wall 60 of the cam receiving chamber 6, andright hand screw threads 10 are formed at the outermost end portion ofthe opening 9.

The top portion of the body 5 is formed with a generally trapezoidalshallow recess ll and a rectangular opening 12 communicating with thespring receiving opening 9.

A recess 51; having a generally trapezoidal configuration is formed inthe rear end portion of the body 5 and a recess 13 having a squarecross-sections and communicating with the recess 5b is formed along theaxis of the body 5. As best shown in FIG. 5, a projection 14:! of a toeclamping member 14 is received in the recess 13 and a vertical adjustingthreaded rod 15 is threaded into the projection 14:! with its upper andlower ends extending through the upper and lower walls of the recess 13in a loose fitting relation thereto. Thus the toe clamping member 14 isheld beneath the trailing end of the body 5 as shown in FIG. 2.

A cam 16 received in the cam receiving chamber 6 is preferably made of aself lubricating substance such as tetrafluoroethylene but othermaterials may of course be used. The cam 16 is provided with verticalside walls 164: slidably engaging the vertical side walls 611 of the camreceiving chamber. A spring seating recess 17 is formed through the foreend surface of the cam 16 in axial alignment with the spring receivingopening 9, and an arcuate cam surface 16/; is formed at the center ofthe rear surface of the cam 16 for cooperating with the pin 4 in amanner to be described later. In the present embodiment, the endsurfaces of the cam 16 on the opposite sides of the cam surface 1612 areflat and perpendicular to the longitudinal axis of the body 5. The abovedescribed form of the cam surface is preferred because of easiness inthe manufacturing thereof. The form of the cam surface is of course notstrictly limited to this particular form but any workable recessed camsurface may be employed.

A compression spring 18 is inserted in the spring receiving opening 9with its inner end sealed against the bottom of the spring seatingrecess 17 and its outer end abutting against awasher 20 urged by acylindrical spring adjusting member 19 which is provided with an axialvertical slot 190 for accommodating pin 3. Righthand screw threads 10provided near the outer end of the spring receiving opening 9 are usedto receive a screw 21 for fine adjustment. The head 22/; of an adjustingscrew 22 having lefthand screw threads 22a mating with the screw threadscut through the outer end wall of the spring adjusting member 19rotatably engages the central opening of the fine adjustment screw 21.The screw 22 is provided with a flange 22(' which is clamped between theouter end wall of the spring adjusting member 19 and the screw 21 forpre venting Withdrawal of the adjusting screw 22. The pitch of thelefthand screw threads 22a is made larger than that of the righthandscrew threads of the fine adjustment screw 21. As shown in FIG. 2, acover plate 23 is used to close the recess 11 in the upper portion ofthe (ill body 5, and the upper ends of pins 3 and 4 are interconnectedby a tie plate 24 for reinforcement. A pointer, not shown, connected tothe spring 18 for indicating a maximum permissible load at which the toeof the skiers boot should be released is provided to extend through theopening 12.

To use the toe piece of this invention described above, the springadjusting member 19 is moved in the axial direction by the adjustmentsof the adjusting screw 22 and the fine adjustment screw 21 so as to urgethe cam surface 16b of the cam 16 against the pin 4 under a suitablepressure. Under these conditions, the body 5 is positioned with its axisaligned with the longitudinal axis of the ski l.

The toe clamping member 14 is adjusted in the vertical direction byturning the screw 15 for receiving the toe of the soleplate of anythickness of the skiers boot.

Due to the forward pressure applied by the heel piece, not shown, of theski binding, the toe of the soleplate is urged into a space defined bythe lower surface of the toe clamping member 14, the lower recessedsurface 512 on the rear end of the body 5, and the upper surface of theski 1 whereby the boot is firmly secured to the ski.

During the normal operation of the ski and within a predetermined rangeof the transverse force acting upon the skiers boot, the body 5 iscaused to merely resiliently oscillate about the pin 3 in a range inwhich the cam surface 1617 does not disengage from the piin 4 by thecooperation of the forward pressure applied by the head piece and thepositioning force applied to the pin 4 by the cam surface 612 of the cam16 under the action of the spring 18. More particularly, as long as themagnitude of the transverse force is within said predetermined range,the body 5 is pivoted about the pin 3 in the direction of the appliedtransverse force against the force of the spring 18. During this rotarymotion of the body 5, the pin 4 is displaced laterally relative to thecam surface 1612, thus producing a restoring force. When the transverseforce disappears, the body 5 will be returned to the original positionby said restoring force. In this manner, the shock applied to the skiboot can be absorbed, thus ensuring the safety of the skiing operation.

When the transverse force exceeds the maximum permissible load preset bythe spring 18, the pin 4 will disengage from the recessed cam surface16b and come into engagement with either one of the flat surfaces on theopposite sides of the cam surface 161), thus rapidly decreasing thepressure applied to the pin 4 by thespring 18 via the cam 16. As aresult, the body 5 is retated about the pin 3 by the applied transverseforce without any appreciable resistance whereby the boot is readilyreleased from the binding thus preventing injury to the skier such asbone fractures.

As has been described hercinabove, the novel toe piece of this inventionincludes only one pivot point or the pin 3 and the toe clamping memberI4 is not rotat able with respect to the body 5. For this reason, thedefect inherent in the prior art toe piece that it becomes inoperabledue to deposition of snow or ice is substantially eliminated. Moreover,if the body positioning cam 16 is made of a synthetic resinous materialsuch as tetrafluoroethylene which has a self lubricating propert at alow temperature enviroment, it is very easy to shape the cam surfacewhich otherwise is required to have a complicated configuration.Moreover, it is possible to fabricate the toe piece of this invention ata low cost because it requires a relatively small number of componentparts of a rugged and simple construction.

Moreover, since the spring pressure is adjusted not only coarsely byadjusting the screw 22 but also finely by the fine adjustment screw 21,it is possible to finely set any desired maximum permissible load atwhich the toe is released. Further. as the screw threads of these twoadjusting screws are cut in the opposite direction with differentpitches. thereis no fear ofrotating one screw which the other is beingadjusted.

In a modifiedembodiment ofthis invention shown in FIGS. 7 and 8, anelongated trapezoidal base plate 31 is provided with a pair of upwardprojections 32 on the rear end thereofand another pair of upwardprojections 33 on the side edgesnear the rear end. the projections 32and 33 being respectively disposed symmetrically with respect to thelongitudinal axis of the base plate 31. The base plate 31 is securelyfastened is the ski. not shown, by means of screws passing throughopenings 34. The inner surfaces of the projections 32 are shaped toconform with a circle having a center on the center line of the baseplate and a radius equal to the distance between the centers of a pivotpin 35 and of an internally threaded sleeve 33a to, be described later.A body 36 pivotally mounted on the base plate 31 by means of the pivotpin 35 is formed with an arcuate slot 37 which is located to the rear ofthe pivot pin 35 and cocentric with the pivot pin 35. The lower end of apressing pin 38 extending through the arcuate slot 37 is caulked to thebase plate 31. A cam receiving chamber 39 is formed in the body 36 toextend in the longitudinal direction thereof. the chamber 39beingdefined by vertical opposite side walls extending from the arcuateslot 37 in parallel with the longitudinal axis of the body and by therear wall of the arcuate slot 37. A cam 40 is received in the camreceiving chamber 39 with its cam surface 40' normally urged against thepressing pin 38 by means of a compression spring 41-. The cam surface40' comprises a generally arcuate recess having its innermost portionaligned with the longitudinal axis of the body 36 and the surfaces onboth sides of the cam surface 40 may be very gradually curved as shownin FIG. 7 or may be flat and perpendicular to the axis of the ski. Anadjusting screw 42 is received in the threaded opening of the camreceiving chamber 39 for adjusting the pressure of the spring 41 appliedto th pressing pin 38, or the safety limit.

Vertically spaced bearings 36a and 3612 are provided for the rear end ofthe body 36 for journalling the sleeve 33. A cup shaped toe clampingmember 44' is provided with a thin axial projection 44' which isrotatably mounted on the sleeve 33a between the bearings 36a and 36b ofthe body 36. An adjustable cup shaped member 45 is mounted on the toeclamping member 44 by means of an adjusting screw 46 received in thesleeve 33a.

A pair of vertical pins 47 extend through'a pair of openings providedthrough the toe clamping member 44 and carry guide rollers 48 near theirlower ends. The pins 47 are symmetrically disposed with respect to thelongtitudinal axis of the body 36. When the toe of the soleplate is heldby the toe clamping member 44, or when the cam surface 40' is urgedagainst the pressing pin 38 so as to coincide the longtitudinal axis ofthe body 36 with that of the ski. the guide rollers 47 engage theafore-mentioned upward projections 32.

.the pivot pin 35, the pressing pin 38 engages a different portion ofthe cam surface 40' thereby compressing the spring 41. The compressionof the spring 41 creates a reactive force proportional to thedisplacement and balancing with the transverseforce. When the transverseforce applied to the boot disappears, the reactive force returns thebody and the toe clamping memberto their original positions. Theresilient rotary movements of the body and the toe clamping memberdescribed above are performed while the pressing pin 38 is maintained inengagement with the arcuate cam surface 40. In this manner, within thesafety limit of the applied transverse force, the toe of the ski boot ispermitted to I resiliently swing about the pin 35 thus assuming a stableoperation of the ski.

Should the transverse force applied to the boot, e.g. upwardly as viewedin FIG. 7, exceed the safety limit, the pressing pin 38 is caused todisengage from the arcuate cam surface 40' and comes to engage thesurface on the lower side of the cam surface 40?. Then, the lower guideroller 48 will be brought to the position between the projections 32whereas the upper guide roller 48 will be caused to roll along thesurface of the upper projection 33 thus rotating the toe clamping member44 in the counterclockwise direction. This increases the compression ofthe spring 41 and the reactive force of the spring .acts obliquelyagainst the pressing pin 38 whereby the pressure applied to the pressingpin 38 decreases rapidly. As a result, the body 36 can rotatefreelyuThus, by the rotations of the cup shaped toe clamping member 44and the body 36, the ski boot' is released from the binding therebyprotecting the provided with a rectangular cam receiving chamber 56 atits rear end. and a longtitudinal spring receiving opening 57 extendingbetween the force ends of the body and the cam receiving chamber. A cam58 preferably made of a synthetic resinous material having selflubricating property. for example tetrafluoro ethylene. is slidablyreceived in the cam receiving chamber 56. Although not shown in thedrawing, the rear end surface of'the cam 58 is provided with. an arcuaterecess or a cam surface which cooperates with the pivot pin 54 and thefront end is provided with a spring receiving opening 59 which iscoaxial with the spring receiving opening 57 to receive acompressionspring 62. Screw threads 60 are cut near the outer end of the spring receiving opening 57 for receiving a spring adjusting screw 61, actingupon the spring 52 through a bottomed cylindrical member 63. For thepurpose of avoiding interference with the pivot pin 53, the cylin dricalmember 63 is formed with a longitudinal slot (not shown The upper endsof pins 53 and 54 are interconnected by a tie bar 64 for reinforcement,

A cover 65 is mounted on the body 55. Referring to FIG. 11 which showsthe cover 65 turned upside down. the cover 65 comprises an upper plate67 having a recess 66 on the surface thereof, an end plate 68 and sideplates 69. The end plate 68 and side plates 69 depend vertically fromthe upper plate 67 and cooperate to form a member having across-sectional configuration of a letter I. The covpr 65 is providedwith openings 70 and 72 for receiving pins 69 and 71, repectively,projecting upwardly from the body 55. The projecting ends of the pins 71are caulked to fasten the cover 65. A pair of windows are formed nearthe opposite ends of the end plate 68 for receiving a pair of toeclamping members 73, the vertical position thereof being adjustable bymeans of bolts 74.

In this modification, the pressure applied to the pin 54 by the cam 56can be adjusted by turning the adjusting screw 61, whereby the safetylimit at which the toe of the soleplate is released is varied, and thevertical position of the toe clamping members 73 can be varied byturning bolts 74 so as to receive the soleplate of any thickness. By theforward pressure applied by the heel piece, not shown. the toe of thesoleplate is urged into a space defined by the lower surfaces of the toeclamping members 73, the vertical wall of the end plate 68 and the uppersurface of the ski, thus securing the boot to the binding.

When a transverse force less than the safety limit is applied to theboot, the body 55 is caused to merely resiliently occillate about pivotpin 54 by the forward pressure applied by the heel piece and thepressure applied upon the pivot pin 54 by the cam 58 under the action ofspring 62.. Under these conditions, the cam surface of the cam 58 willnot disengage from the pin 54, In other words. as long as the transverseforce applied to the boot is smaller than a predetermined safety limit.the toe is held by the toe clamping members 73 and the shock can beabsorbed by the swinging motion of the body 55 about the pivot pin 53.

However, when the transverse force exceeds the safety limit which is setby the adjustment of the spring 62, the pin 54 disengages the camsurface of the cam and rides on either one of the flat portions of theend surface of the cam which are located on both sides of the arcuatecam surface. Then, the pressure provided by the spring 62 is appliedobliquely upon the pin 54 so that the body 55 is quickly rotated in thedirection of the transverse force about the pin 53, thereby releasingthe boot from the binding.

In this embodiment too, the toe piece is rotatable about only one pivotpin 53 and the toe piece clamping members 73 do not rotate with respectto the cover and the body. Moreover. the configuration of the cam isextremely simple and, since it is made of a self lubricating materialsuch as tetrafluoroethylenc, the toe piece can operate accurately evenunder extremely low temperature conditions.

Like the first embodiment, fine adjustment of the spring can be providedby using two adjusting screws provided with righthand and lefthand screwthreads respectively. It should also be understood that two toe clampingmembers 73 may be combined into a single piece adjustable in thevertical direction.

What is claimed is;

1. In a toe piece of a safety ski binding of the type including arotatable toe clamping member which acts to normally clamp the toe ofthesoleplate of a ski boot but is rotated to release the toe when atransverse force exceeding a predetermined limit is applied to the boot,the improvement which comprises a base plate to be secured to the ski,first and second pins which are secured to said base plate near the foreend and the rear end thereof respectively, a body pivotally mounted onsaid first pin located near the fore end, said body being provided witha cam receiving chamber near the rear end thereof, a cam received insaid cam receiving chamber to be slidable in the direction of the axisof the ski, the rear end surface of said cam being provided with arecessed cam surface engageable with said second pin near the rear endof said base plate, a compression spring contained in said body in theaxial direction thereof for normally urging said recessed cam surfaceagainst said second pin, means for adjusting the force of said spring,and a toe clamping member secured to said body at the rear end thereof,whereby when a transverse force exceeding a predetermined safety limitpreset by said spring is applied to said boot, said second pin is causedto disengage from said recessed cam surface thereby to allow said camand said body to rotate about said first pin for releasing the toe fromsaid toe clamping member.

2. The toe piece according to claim 1 wherein said toe clamping memberis provided with a forwardly projecting projection received in anopening of said body and said toe clamping member is connected to therear end of said body by means of a bolt so as to be adjustable in thevertical direction.

3. The toe piece according to claim 1 wherein said body is provided withan arcuate slot concentric with said first pin for receiving said secondpin.

4. The toe piece according to claim 1 wherein said spring adjustingmeans comprises a pair of cooperating adjusting members provided withoppositely directed screw threads.

5. The toe piece accordihg to claim 1 which further includes acylindrical member interposed between one end of said spring and saidspring adjusting means and said cylindrical member is provided with alongitudinal slot for receiving said first pin.

6. The toe piece according to claim 1 whi h further includes means forpivotally connecting said t e clamping member to the rear end of saidbody, guide rollers provided on said toe clamping member and projectionsformed on the rear end portion of said base plate and engageable withsaid guide rollers for restraining rota- .tion of said toe clampingmember in a normal position of use.

7. The toe piece according to claim 1 which further includes a coverplate secured to the upper surface of said body, said cover plate havinga vertical end plate which depends from the rear end thereof and has across-sectional configuration of a letter l. said end plate being formedwith a pair of windows near both sides thereof, and a pair of toeclamping members mounted in said windows by means of bolts by which thevertical position of said toe clamping members is adjustable.

8. The toe piece according to clam 1 wherein said earn is made of a selflubricating substance.

1. In a toe piece of a safety ski binding of the type including arotatable toe clamping member which acts to normally clamp the toe ofthe soleplate of a ski boot but is rotated to release the toe when atransverse force exceeding a predetermined limit is applied to the boot,the improvement which comprises a base plate to be secured to the ski,first and second pins which are secured to said base plate near the foreend and the rear end thereof respectively, a body pivotally mounted onsaid first pin located near the fore end, said body being provided witha cam receiving chamber near the rear end thereof, a cam received insaid cam receiving chamber to be slidable in the direction of the axisof the ski, the rear end surface of said cam being provided with arecessed cam surface engageable with said second pin near the rear endof said base plate, a compression spring contained in said body in theaxial direction thereof for normally urging said recessed cam surfaceagainst said second pin, means for adjusting the force of said spring,and a toe clamping member secured to said body at the rear end thereof,whereby when a transverse force exceeding a predetermined safety limitpreset by said spring is applied to said boot, said second pin is causedto disengage from said recessed cam surface thereby to allow said camand said body to rotate about said first pin for releasing the toe fromsaid toe clamping member.
 2. The toe piece according to claim 1 whereinsaid toe clamping member is provided with a forwardly projectingprojection received in an opening of said body and said toe clampingmember is connected to the rear end of said body by means of a bolt soas to be adjustable in the vertical direction.
 3. The toe pieceaccording to claim 1 wherein said body is provided with an arcuate slotconcentric with said first pin for receiving said second pin.
 4. The toepiece according to claim 1 wherein said spring adjusting means comprisesa pair of cooperating adjusting members provided with oppositelydirected screw threads.
 5. The toe piece according to claim 1 whichfurther inCludes a cylindrical member interposed between one end of saidspring and said spring adjusting means and said cylindrical member isprovided with a longitudinal slot for receiving said first pin.
 6. Thetoe piece according to claim 1 which further includes means forpivotally connecting said toe clamping member to the rear end of saidbody, guide rollers provided on said toe clamping member and projectionsformed on the rear end portion of said base plate and engageable withsaid guide rollers for restraining rotation of said toe clamping memberin a normal position of use.
 7. The toe piece according to claim 1 whichfurther includes a cover plate secured to the upper surface of saidbody, said cover plate having a vertical end plate which depends fromthe rear end thereof and has a cross-sectional configuration of a letterI, said end plate being formed with a pair of windows near both sidesthereof, and a pair of toe clamping members mounted in said windows bymeans of bolts by which the vertical position of said toe clampingmembers is adjustable.
 8. The toe piece according to clam 1 wherein saidcam is made of a self lubricating substance.